The present invention relates generally to catheters used in angioplasty and perfusion procedures and more particularly, to a passive perfusion catheter which relies upon the blood flow within a vessel for perfusion.
Atherosclerosis is a condition characterized by fatty deposits accumulating on the interior walls of blood vessels. These deposits build up and harden and may build up to the point where they substantially block the flow of blood through the vessel. These blockages are referred to as stenoses. There are a variety of procedures and equipment used in the treatment of stenoses. The use of inflatable balloon, or dilation, catheters to treat such blockages is widespread. These balloon catheters are often used in percutaneous transluminal coronary angioplasty (PTCA) to treat such blockages by expanding against the blockage.
In PTCA, a guidewire is introduced into the artery of the patient and guided through the artery until the distal tip of the catheter is in the desired location of the blood vessel near the stenosis. A dilation catheter which has an inflatable balloon affixed to its distal end is then introduced along the guidewire and advanced into the patient until the balloon end, i.e., the distal end, is located at the stenosis. Once properly located, the balloon is inflated so that it expands against the artery walls, thereby expanding or dilating, the blood vessel and compressing the stenosis. This expansion often removes all of or a significant portion of the blockage. The balloon may be inflated against the arterial walls for one specific time or it may be repeatedly inflated and deflated in a cycle matching the heartbeat of the patient. Once the blood vessel is expanded, the balloon is deflated and the balloon and guidewire are removed so that blood may again flow through the blood vessel.
Restenosis is a condition where the blood vessel wall is expanded by the balloon and the blockage is opened, but the blood vessel wall contracts and adopts its original restricted state some time after the balloon is deflated and removed. The rate of restenosis may be lowered if longer inflation times are used during balloon catheterization procedures.
However, longer balloon inflation times may promote the occurrence of ischemia of the cardiac muscles and of the area surrounding the blood vessel. Ischemia is a local or temporary deficiency of oxygen in an area of the body caused by an obstruction in the blood vessel which supplies blood to that area. In order to prevent ischemia, perfusion catheters are used in association with balloon catheters and especially with coronary angioplasty catheters. Perfusion catheters are catheters which permit the continued flow of blood during the inflation of the balloon.
The perfusion of blood through a balloon at the distal end of a catheter may be accomplished in a number of ways. For example, an angioplasty balloon may be used which has one or more dedicated passages which define flow channels extending through the balloon from one end to the other to permit the passage of blood past the balloon and through the blood vessel. Alternatively, the balloon catheter itself may have a separate lumen dedicated as a fluid passage which extends through the catheter past the balloon, so that blood may be aspirated from another body location and pumped into the blood vessel past the blockage. In use, the balloon is inflated and deflated while blood is perfused through the balloon through a perfusion lumen. In such catheters, these pumps may be mechanically powered or may be hand-powered. In any event, when such pumps are used, they may create pressure pulses during operation. They may also affect the ability to perfuse blood through the vessel in vessels of small diameter.
The present invention is directed to a passive perfusion catheter which does not primarily rely upon an external pump and which has a bifurcated distal end portion having two separable, aligned components which may be displaced from alignment with each other to expose the openings of a perfusion lumen to the blood flowing within the blood vessel so that the flow of blood itself maintains perfusion through the distal end porion of the catheter.
Therefore, the present invention in one principal aspect includes a balloon catheter having a bifurcated distal end portion which includes two distinct components, one of the components supporting a dilation balloon and containing a perfusion lumen, the other of the two components containing a plurality of lumens, the one component being displaceable from an insertion position wherein the interior lumens of both components are axially aligned together along the length of the catheter to a perfusion position wherein a perfusion lumen is aligned within the blood vessel which permits the flow of blood through catheter.
In another principal aspect of the present invention, both catheter components include a guidewire lumen and an inflation lumen running therethrough which are aligned together when the catheter components are aligned in the insertion position. This position permits insertion and advancement of the catheter along a guidewire through the blood vessel to the site of the stenosis. The inflation lumen also extends through both catheter components when aligned in the insertion position and remains in alignment when the catheter is moved to a perfusion position wherein the component's perfusion lumen is aligned with the blood vessel and not with any lumen of the catheter.
In still another principal aspect of the present invention, the inflation lumen of the two catheter components serves to interconnect the components by means of a transit tube which permits displacement of one catheter component relative to the other catheter component. In a preferred embodiment of the invention this movement is rotational, so that when the catheter distal end portion is inserted into a blood vessel and positioned in place at the stenoses, a physician need only twist the proximal end of the catheter to displace the distal end portion of the catheter from the rest of the catheter.
It is therefore an object of the present invention to provide an improved perfusion catheter having a bifurcated distal end defining two components of the catheter which permits movement of one component relative to the other component.
Another object of the present invention is to provide a passive perfusion catheter which relies upon the flow within a blood vessel to accomplish the perfusion without the aid of an external pump.
Still another object of the present invention is to provide a perfusion catheter having a bifurcated distal end portion dividing the catheter into two components, each of the components having distinct guidewire and inflation lumen portions, these portions being axially aligned together when the catheter is in an insertion position, the two components being moveable out of alignment with each other by twisting or rotating the catheter so that the inflation lumen portions are aligned but the guidewire lumen portions are not aligned, the one catheter component containing a perfusion lumen which is exposed and defines a fluid passage within a blood vessel when displaced from the other catheter component.
Yet another object of the present invention is to provide a method for dilating a blockage within a blood vessel while possibly perfusing blood past the blockage by inserting a catheter of the aforementioned construction into a blood vessel, locating the distal end portion of the catheter carrying an inflation balloon, manipulating the catheter to displace the distal end portion out of alignment with the rest of the catheter thereby exposing the perfusion lumen thereof, and inflating the balloon while permitting blood to perfuse past the balloon.
These and other objects, features and advantages of this invention will be clearly understood through a consideration of the following detailed description.